1. Field of the Invention
The present invention relates to novel polyorganosiloxanes comprising propanaldehyde functional groups and to a process for the preparation of such novel polyorganosiloxanes by hydroformylation.
2. Description of the Prior Art:
The preparation of a silane containing a propanaldehyde functional group, namely, of the type .tbd.Si--CH.sub.2 --CH.sub.2 --CHO or ##STR2## by hydroformylation of the corresponding vinylsilane utilizing various catalysts has already been described in the scientific literature.
Thus
(i) in J. Oro. Chem., 17, p. 1107-1109, the hydroformylation catalyst is based on cobalt;
(ii) in the Journal of General Chemistry of the USSR (translation of Zhurnal Obshchei Khimii, p. 1395-1397 of 20 Dec. 1977), vol. 47, number 7, part 1 (July 1977), the catalyst is rhodium-based; and
(iii) in EP-A-89,690, the catalyst is preferably rhodium deposited on alumina.
However, insofar as the present applicants are aware, the chemical literature does not describe the production of polyorganopolysiloxanes containing a propanaldehyde functional group by a hydroformylation process, or by any other preparative process. Only the disiloxane of the formula: EQU (OHCCH.sub.2 CH.sub.2)(CH.sub.3).sub.2 Si--0--Si(CH.sub.3).sub.2 (CH.sub.2 CH.sub.2 CHO)
is described, in J. Org. Chem., vol. 35, number 12, p. 4180-4183 (1970), and this is prepared by a process entailing the hydrolysis of a disiloxane precursor.
Furthermore, also insofar as the present applicants are aware, no description exists in the prior art of a vinylsilane hydroformylation process being carried out in the presence of a catalyst system containing rhodium and sulfonated or carboxylated triarylphosphine salts.
Such a hydroformylation process, applied to organic olefins, is described in FR-A-2,314,910 in the case where the phosphine salts are water-soluble, and in U.S. Pat. No. 4,740,626 in the case where the phosphine salts are soluble in organic solvents, insoluble in water, but soluble in an aqueous solution of a base.
In FR-A-2,314,910, the hydroformylation reaction is described as being carried out in aqueous phase. In U.S. Pat. No. 4,740,626, it is described as being carried out in an organic phase.